The present invention relates to fuel injection pumps of the type having a pump body with pumping chamber having a plurality of plunger bores, a plunger mounted in each plunger bore for reciprocation, one or more cams providing periodic intake and pumping strokes of the plungers for supplying intake charges of fuel to the pumping chamber and delivering high pressure charges of fuel from the pumping chamber for fuel injection, and a distributor system for distributing the high pressure charges of fuel from the pumping chamber sequentially to a plurality of fuel injectors of an associated internal combustion engine (such fuel injection pumps being referred to herein as "Distributor Type Fuel Injection Pumps").
Distributor Type Fuel Injection Pumps normally employ a rotary distributor for distributing the high pressure charges of fuel sequentially to the fuel injectors. The rotary distributor conventionally comprise a distributor head with a plurality of distributor outlets, one for each fuel injector, and a rotor mounted for distributing the high pressure charges of fuel sequentially to the distributor outlets. In such pumps, the pump body may be fixed or rotatable, and which, if rotatable, is usually rotatable with the distributor rotor. Because the fuel charges are delivered at a high pressure, the relatively rotating surfaces of the distributor head and rotor are required to have a very precise rotational fit (for example, having a diametral clearance of 80-100 millionths of an inch) to ensure adequate sealing and lubrication. If the pump body is fixed, the relatively rotating surfaces of the pump body and distributor rotor are required to have a similar rotational fit for supplying the high pressure charges of fuel from the pumping chamber to the rotor. Distributor type fuel injection pumps with either a fixed or rotating pump body have the following disadvantages:
(a) the required precise fit of the relatively rotating surfaces substantially increases the cost of manufacture and assembly of the pump;
(b) during pump operation, particularly at high speed, a substantial amount of heat is generated by the thin layer of fuel lubricant between the relatively rotating surfaces;
(c) adequate lubrication of the relatively rotating surfaces is difficult to achieve at high speed and with low viscosity fuels such as gasoline and methanol;
(d) the temperature of the distributor head must be maintained at approximately the same temperature as the distributor rotor throughout the full range of operation of the pump and particularly as the rotor temperature increases rapidly during cold starting and rapid acceleration; otherwise, the resulting unequal thermal expansion of the parts will cause inadequate lubrication and rotor seizure; and
(e) a charge delivery pressure of 12,000 psi and higher is difficult to achieve due to thermal, rotational and structural aspects of conventional rotary distributor pump design.
In certain conventional Distributor Type Fuel Injection Pumps having a rotary distributor, the plungers are mounted for radial reciprocation in a pump body which rotates with the distributor rotor to deliver the high pressure charges of fuel directly to the distributor rotor. This type of pump has certain additional disadvantages and problems because of the centrifugal force on the plungers and the valving and sealing problems associated with supplying fuel to and/or spilling fuel from the rotating pump body. Some pumps of this type employ an electromagnetic control valve for controlling the size and/or timing of each high pressure charge by regulating the intake charge quantity of fuel and/or the spill timing of the beginning and/or ending of the fuel injection event. There are additional disadvantages and problems associated with the use of an electromagnetic control valve for supplying fuel to and/or spilling fuel from the rotating pump body.
A principal aim of the present invention is to provide a new and improved Distributor Type Fuel Injection Pump having a distributor system which avoids the disadvantages and problems associated with the use of a rotary distributor and rotating pump body.
Another aim of the present invention is to provide a new and improved Distributor Type Fuel Injection Pump having a high pressure chamber with a small dead volume and capable of delivering charges of fuel at 12,000 psi and higher.
Another aim of the present invention is to provide a new and improved Distributor Type Fuel Injection Pump of the type having a non-rotating pumping chamber body and providing one or more of the following advantages over conventional Distributor Type Fuel Injection Pumps of that type:
(a) capable of delivering charges of fuel at higher pressure;
(b) useful with low viscosity fuels such as gasoline and methanol;
(c) capable of being manufactured and assembled more economically and with fewer parts; and
(d) provides improved performance over a full range of pump operation.
Another aim of the present invention is to provide a new and improved Distributor Type Fuel Injection Pump having a non-rotating pumping chamber body and a cooperating electromagnetic control valve which together provide the following advantages:
(a) high pressure chamber with small dead volume;
(b) improved valve responsiveness;
(c) low valve wear and long useful valve life;
(d) high electromagnetic actuating force;
(e) low manufacturing cost; and
(f) precise control of the size and timing of the injected fuel charge.
A further aim of the present invention is to provide a new and improved Distributor Type Fuel Injection Pump having a supply pressure regulator and electromagnetic control valve which cooperate to provide one or more of the following advantages:
(a) inlet pressure regulation and fuel accumulation to provide high rate of fuel delivery to the high pressure chamber during the intake strokes; and
b) operable to spill hot fuel from the pumping chamber during the pumping strokes and to divert hot spilled fuel from being directly resupplied to the pumping chamber during the following intake strokes.
A further aim of the present invention is to provide in a Distributor Type Fuel Injection Pump of the type having a non-rotating pumping chamber body; a new and improved system for
(a) supplying fuel from a supply pump to the high pressure chamber during the intake strokes; (b) controlling the fuel inlet pressure to ensure an adequate supply of fuel to the high pressure chamber during the intake strokes; (c) spilling fuel from the high pressure chamber without excessive back pressure during the pumping strokes; and (d) distributing the high pressure charges of fuel from the high pressure chamber to the distributor outlets in a new and improved manner which does not required a distributor rotor.
In accordance with another aim of the present invention, a new and improved Distributor Type Fuel Injection Pump is provided which (a) can be more economically manufactured; (b) can deliver charges of fuel from the high pressure chamber at 12,000 psi and higher; (c) can be used with internal combustion engines having two to eight cylinders or more; (d) has a modular design with only a few parts specifically designed for the number of fuel injectors; and (e) is electrically controlled to precisely regulate the size and/or timing of the injected fuel charge.
Other objects will be in part obvious and in part pointed out more in detail hereinafter.
A better understanding of the invention will be obtained from the following detailed description and the accompanying drawings of illustrative applications of the invention.